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Gravity II

Northern Ireland Water
£4 million
January 2014 - November 2014

Gravity II was by far the highest profile trunk main rehabilitation project undertaken by Northern Ireland Water (NIW) within an urban environment to date. The scope of the works involved 5.1km of 710mm HPPE being slip-lined through 33” PS concrete which were laid through urban North Belfast streets, through residential gardens and 2 well established golf courses between two major North Belfast reservoirs.

Extensive Enabling CCTV identified the condition of the existing pipeline which, when commissioned in 1967, survived only 15 years before being decommissioned again in 1982. Gravity II brought this back to life and enabled NIW to utilise an asset capable of delivering 32ML (mega-litres) of water per day to North Belfast, which would provide clean drinking water to over 100,000 people.

From the extensive enabling, CCTV determined that the host pipe had a number of engineering constraints requiring solutions to allow the new pipe to be put in. This process also revealed that since its completion in 1967, the land adjacent to the host pipe had become more and more built up with houses, gardens, NIE sub-stations and other such obstructions on or near the wayleave, which had to be navigated around by the construction team.

Up to 4 gangs were employed over the 44 week program in order to fulfil the proposals with 25,000 man hours being worked within this time, ultimately resulting in the works being completed within budget target, on time with the program detail and with all snag works carried out within 1 week of commissioning taking place

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